Cellular interactions in the human immune response to the herpesviruses will be studied using: (a) purified preparations of monocytes, cultured macrophages and lymphocyte subpopulations; (b) measurements of lymphocyte proliferation and interferon (IFN) production; and (c) different forms of herpesvirus antigen, including cell membrane-associated antigen, and, where possible, purified virions and soluble protein antigens. Interferon production will be investigated with particular attention to the interactions among monocytes, macrophages and lymphocyte subpopulations and the conditions required for the production of IFN-alpha (Type I, leukocyte) and IFN-gamma (Type II, immune). For comparison, IFN will also be elicited from these cells by mitogens, non-viral antigens, and non-specific inducers. The modulation of IFN production by interactions among different cell populations and the mechanisms of those interactions will be examined.